1. Technical Field
The present invention relates to a carbon-nano tube (CNT) structure, a method of manufacturing the same, and a field emitter and a display device, each adopting the same.
2. Related Art
With the disclosure of the structural and electric characteristics of CNT, studies of CNT have been performed to apply the CNT to various devices, such as field emitters, transistor and secondary batteries. More specifically, CNT used as an emitter of a field emission display (FED) has various merits, such as low operation voltage, high luminance and low price, and the application of CNT to an emitter will be commercially used within a short time. Examples of methods of manufacturing CNT include a screen printing method using CNT powder, and a method using chemical vapor deposition (CVD). The method using CVD has been actively studied because such a method can be used to manufacture a display device with high resolution, and requires a simple process of growing CNT on a substrate. Examples of CVD include plasma enhanced chemical vapor deposition (PECVD) and thermal chemical vapor deposition (thermal CVD).
In order to manufacture a high-quality FED, CNT used as an emitter should have a low operation voltage, a high electron emission current, and uniform characteristics over a large area. CNT can have a low operation voltage and a high electron emission current when the CNT has a small diameter and is formed to a proper density. The diameter of CNT depends on the size of a catalyst metal, which exists on the CNT, such that a smaller catalyst particle can produce CNT having a small diameter. In addition, the CNT should be formed in one direction so as to control the density of the CNT, and the temperature of a growth system should be uniform so as to obtain uniform electron emission over a large area.